Answer:
You need a compass and a ruler
Step-by-step explanation:
Open your compass to a certain amount and don't change it. Put the compass point on p, and swing the pencil over line m on the left side, and then the right. These new points will be called a and b. Then put the compass point (without changing the opening) on point a and make an arc below line m. Do the same with point b. Where those arcs cross will be point c. Connect point P and point c with a ruler. This line is perpendicular to line m. (See image)
